Crawler tread mechanism



Oct. l1, 1932. G. c. JETT CRAWLER TR-EAD MEGHANISM Filed Deo. 15. s sheets-snet 1 wwwA A TTORNEY.

Oct. 1l, 1932. v G, C, JET-r 1,881,630

CRAWLER TREAD MECHANI SM Filed veel.. 15. 1927 sheets-sheet 2 I JNVENTOR. 550555 5.' L/TT.

ATTORNEY.

oct. 11, 1932. G, c, JETT 1,881,630

CRAWLEF. TREAD MECHANISM Filed Dec. l5. 1927 3 Sheets-Sheet 5 IN VEN TOR. 550555 U'TT.

A TTORNE Y.

Patented Oct. 11, 1932 U'NirED Shirtsv PATENT orrlcs MILWAKEE, WISCONSIN, AssIGNoa or Two-rrr'rns To' WALTER H. vsTInIvIKE, or MILWAUKEE, WISCONSIN onewnnn Tinian MECHANISM Application tiled December'l, 1927. Serial No.`240,141. l

.This invention relates to crawler? tread mechanisms and particularly to endless tread belts of the self-sustaining type capable of providing a substantially rigid track for the end rollers orvtumblers without requiring the use of intermediate rollers so commnlyem-y f ployedvto sustain the belt againstbuckling under load.

'.On'eobject of the present invention is'to provide an improved high `capacity tread belt of the type mentioned of rugged, simple, and economical design. l

Other more specific objects and advantages will appear from the following description invention. f' Y In the drawings j A 'Figurel is a viewinv side elevation lof a crawler tread mechanism constructed in accordance Vwith the present invention.

l Fig. 2 is a horizontal sectional view.

Fig. 3 is a fragmentary sectional view on Aa largerscale of the tread belt shown inFigures 1 and 2. yT his View is taken substantially along vthe line 3-3 of Figure 4. .Y Y Fig. 4L is an inner plan view partly in section, of thatportion of the tread belt shown in Figure 3.

of an illustrative embodiment ofthe present Fig. 5`is a view in side elevation of an end loop of the tread belt showing the relative disposition of the parts when the belt is flexed about an end roller or'tumbler.

The crawler tread mechanism shown com# prises a substantially rigid truck frame preferably in theform of a one-piece VH- shaped casting having a pairY of laterally spaced, v substantially parallel, f longitudinal members 11, integrally;,connected intermediatetheir ends by a cross member 12. The members 11 and 12 are preferably of hollow lbox-section design in order to provide maxi,- lmum strength with vmininfum weight.A The truclr'frame shown isrockablymounted intermediate its ends upon aspindle 13 projecting horizontally from a supporting bracket 14 of a well known type.v In this instance the spindle is journaled in an appropriate bear# ing sleeve 16 removably `seatedwithinv the hollow cross member 12 and locked in vposition bykappropriate means suchas cap screws 17,

which pass throughan end ange 18 on the sleeve. A nut 19 threaded upon the end of the spindle coacts with a washer 2O and shouls der 21 to retain the spindle against end play y within the sleeve.

l A pair lof end rollers or tumblers 22 and 23, mounted at the opposite ends of the frame 10, intermediate the longitudinal members 11, constitute a support and guide for the endless tread `belt 2l to be hereinafter described. In this instance roller 22 is journaled upon an appropriate bushing 25 carried by a fixed shaft 26 projecting lthrough the adjacent ends of the longitudinal members 11 and securely anchored therein by appropriate 1neans,si.1ch as nuts 27 threaded upon theopposite ends ofthe shaft. yThe bushing 25 serves as a spacer element for the ends ofthe members 11 and, coacting withthe shaft and clamp nuts 27, provides arigid tie between those members to thereby increase the strength and rigidity of the frame. The other roller 23 is similarly journaled upon a bushing 28 carried by a shaft 29, which projects through and is similarly anchored in a pair ofslide blocks `30 guided in appropriate ways 31 formed in the other ends of the longitudinal members 11. ln this instance the outer ends of the ways 31' are closed by tiebars 32 cast integral with the members 11. Each tie-bar 32 not only holds the'ways 31 against' spreading but eachfalso eo-acts with an adjusting screw 33, projecting from each slide block 30,'to eli-ect adjustment of the blocks and shaft 29 longitudinally of the ways. Each screw'33 carries nut 34C and lock nut 35. Y A

Each of the end rollers or tumblers 22 and 23 is formed witha relatively deep hub 36, presenting'a relatively wide bearing surface to the bushing 25 or 28, and carrying a series of spokes 37. of double-channel section providing maximum strength with minimum weight. The outer portions 38 of the spokes are forked and merge into two parallel rim portions 39, designed to ride'upon the tread belt, and spaced apart to form a guide channel for the belt. Each rim is preferably reinforced by a circular web 40 which kmerges v j an adjusting therewith and with the outer ends of the spokes.

'The tread lbelt shown comprises a series of hingedly connected track shoes 41 each in the form of a hollow casting having a laterally extended outer plate 42, presenting a broad tread surface to the ground, and a Y pair of laterally spaced inner plates Y43, providing runways forv the rims 39 of the end rollers. A hollow open ended projection' 44 on each shoe, intermediate the plates 43 co' acts with and between the rims l39 to guide and retain the tread belt on the end rollers. The side walls 45 of each proj ection-.44 extend from the adjacent plates 43 of the shoe and merge into a cover plate 46 vrconstituting the inner-extremityof the projection.V Oneend eachpin48'is'removably Xed withinthe l Y of-each side -wall is preferably cut away,

as indicated atf47 to afford ready access to the interior of each projection, for a purpose whichlwilllater appear and to permit `the ready extrusion of foreign matter therefrom.

Successive shoesare connected by appropriate-hinge pins 48 each projected through two seriescf `closely meshed lugs 49 and 56, re-

spectively, projecting from the adjacent edges -ofl successiveshoes. In this instance series of lugs 49 of one shoe by appropriate means,'such asian anchor pin 51, and is ,journaled in appropriate bushings 52 seated lin each Vvof the series of 'lugs'50 of the other-shoe. Y

Each bushing 52 is* preferably 'eccentrically bored, asvindicated in-Figure, so that'a rotative change inthe position thereof will effect 'a variationin 'the shoe pitch. Each bushing, in the Ytread vbeltv shown, is releasablyjheldl'against rotation by appropriate vmeans such as a key 53,so thata predetermined adjustment between successive shoes may behad by withdrawing and reinserting the' bushing end for end to thereby reverse y the direction ofv eccentri'city thereof.

It-will vbe notedthat the hinge connection `betweensuccessive track shoes permit free flexing of the belt in such direction as to permit the 'same to travel about'the end rollersv eral characteristicsisn'otbroadly new the treadbelt shown involvescertain important structural features which are new and which afford numerous structural,l and functional ladvantagesfhereinafter pointed out. In this instance each track shoe 41 carries a pair of posts' 54 securely.y anchored in the plate V46 v and preferablyconnected'by y'a bridge piece 55 to increase the strength andfrigiditybf the posts. The posts 54 andbridge piece 55 are preferably-.formed from a Single Piece 0f a threaded stem 59 projecting from the head.

Theposts 54, bridge piece 5v5, and plate 46 together form a closed link, hereinafter termed'an anchor link, Awhich is connected with the Vcorresponding `links of adjacent shoes through loose connector links 6() slidably engaged therewith.V Each connector link 60 also comprises a high quality steel forging of simple formhaving Ysubstantially parallel side bars 61 connected by end portions 62.

vEach end portion 62 is closely but freely guided between the'bridge piece v55 and plate 46 of the associated anchor link and the side bars 61 straddle'the posts 54 and are similarly guided by .them so'that theIv connector links linksa The inner active'faces .163 of the posts are preferably curved longitudinallyandperipherally to Vmatch the peripheraland lon .gitudinal curvatures of the coacting faces 64 of the end portions 62 of the connector links, as indicated in Figures 3 and 4, sothat each makes full face contact with Ythe other to better withstand Ithe wear and sustain the high pressures to Vwhich, they are subjected. In the upper and lower runs of the tread belt these faces 6 3V and 64 react to effectually limit the -pivotaliaction ofv'successiveV shoes in such-direction'as to preventinward buckling of the tread belt. Eac'hrun of the belt thus formsa rigid beam construction, spanning the space betweenthe-end rollers 22 'and 23,

in which'the anchor and connector links are under tension and the track shoes 41 Vunder compression transmitted through` the hinge pins 48." The anchorand connector links are preferably ofsuch length as compared with the spacing between hinge pins 48th'at the upper andlower runsofythe belt are bowed slightly outwardly. This relation maybe varied by adjusting the bushings 52 in the manner hereinabove described to thereby vary the bowed condition of the tread belt and'to compensate for wear." K

Referring particularly to the lower run of the tread belt it will be noted that for a given loadthereon the tension in the 'anchor and connector links is yinversely proportional to the height thereof above the .hingeepins 48, orv in other words the abilityof the belt to resist buckling under load'increases as the height of the linksincreases. On the other -hand the greaterthe height of the links the greater the slack-required to' permit thetread belt to `travellab'out-the endrollers: All of the slack within an endloop of the-tread belt isconsumed when the-successive connectorv links comprised therein have assumed an end Ito-endV abutting relation, as indicated in Figure 5,- and from an'inspectionrof this are always, properly aligned with the anchor Y figure it will be note-d that the total slack actually provided within the end loop is prothe links above the hinge pins 48 to thereby actually increase theability of the tread belt toiresist inward buckling under load. rlhe outer faces of eachend portion 62-of a-connector link are rpreferably symmetrically bevelled, as indicated at`651, to provide full bearing surfaces for contact with the corresponding'faces of adjacent connector links, and to Y Vprovide a minimum spacing between conthan the connectorlinks. space a within each anchor link may be made,

nector links andV consequently a maximum total slack between the links comprised'within each end loop of the'tread belt. Although VVthe end portions 62 of each connector vlink are made as slender as possible, consistent with the stresses involved, the side bars 6l are preferably made somewhat heavier in or der to prevent excessive stretching and thus preserve the above mentioned outwardly bowed condition at the lower run of the tread belt. i

For smooth running the spacing of the end rollers 22 and 23 and the tension in the tread belt is such that maximum angular deflection between successive track shoes occurs at point adjacent'the lower end .of each t'read'belt loop. It will'be noted from Figure 5 that at this point the ends of the anchor links of adjacent shoes areV in abutting` relation and their lengths thus limit the degree of angular deflection between the shoes. The lengths of the anchor linksare thus limited by the amount of vdeflectionrequired at this point and in the tread belt shown it will be lnoted that the anchor links are somewhat shorter In order that the aslong as possible the width of the posts 54 is reduced as much as possible, consistent with the stresses involved, and in this instance the posts are of substantially the same width as the end portions 62 of the connector links. For the same reason the posts are preferably outwardly bowed. A

By reason of the simple form of anchor and *connectorV links hereinabove described they may be economically produced by simple die forging methods from high grade steel of sniiicient strength and'toughness to withstand severe stresses and wear. The open form of anchor links with their Vends anchored in the track shoes" permits ofeasy assembly and dismantling of the tread belt. In

= this connection it will be noted that the anof the connector linksv is such` as to pass freely between the spaced rims 39 of the end rollers 22 and 23 and thus serve as additional guides for the tread belt which insure entry and reentry of the guide projections 44 of the track shoes between the rims 39 of the end rollers. It will also be noted that the limited extent to which the anchor and connector links project from the track shoes permits the use of single rather than double end rollers thus simplifying and reducing the cost of the crawler unit.

Various changes my be made in the embodiment of the present, invention without departing from or sacrificing any of the advantages of the invention as defined in the appended claims.

claim l l. In a truss-type tread belt for crawler mechanisms the combination of a series of hingedly connected shoes cooperating to form an endless tread belt, an intermediate projection extending inwardly from each shoe, an anchor link having leg portions removably fixed in said projection of each shoe, and connector links interengaged with the anchor links of successive shoes and cof acting therewith to limit the hinge action between said shoesV 2. In a trussety'pe tread belt for crawler mechanisms the combination of a series of hingedly connected shoes, an intermediate hollow projection extending inwardly from each shoe,v an anchor link projecting inwardly from each projection, each link having leg portions seated in said projection, securing means for said leg portions within said projection, openings in said projection providing access to said securing means, and connector links connecting the anchor links of successive shoes.

3. In a truss-type tread belt for crawler mechanisms the combination of a series of shoes, hinge connections between said shoes, an elongated anchor link projectinginwardly from each shoe, and connector links each interengaged with the anchor links of successive shoes and coacting therewith to limit the hinge action between shoes.

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4. In a truss-type tread belt for crawler mechanisms the combination of a series of shoes, hinge connections between shoes, an anchor link projecting inwardly from each shoe, connector links each interengaged with the anchor links of successive shoes to limit the hinge action between shoes in one direction, said connector links being arranged to abut each other to thereby limit the hinge action between shoes in the other direction, the abutting faces of said connector links being bevelled to increase the bearing area thereof.

5. In a truss-type tread belt for crawler mechanisms, the combination of a series of shoes, hinge connections between said shoes, an anchor link projecting inwardly from each V,ai

, 6. In a'.trusstype tread belt for crawlerV mechanisms, the combination of a series of shoes, hinge connections between said shoes, an'inward; .projection on` each shoe, sockets adjacent the endsofsaid projection, a U- shaped anchor link, the ends of said yanchor v link being liXed lin-said sockets, and connector tween the vanchor links of4 successive `slices to lvat Vsaid shoes. 1

linksinterengaged with and betweensaid an- Chor links t0 limit Vthe hinge action between 7. In a truss-type tread beltvfor ,crawler mechanisms, the combination of a series f of shoes, hinge Vconnections between said shoes, an inwardly disposed hollow yprojection on each shoe, openings in said hollow projection, a U-shaped anchor link, the ends of said .anchorlink being seated in'l said openings,

means within said hollow projection Jer releasably fixing said ends in said openings,and connectorylinks interengaged with and belimit vthe hinge` action between saidshoes.

8. In a truss-type tread beltfg'icor crawler mechanisms, the combination of aseries of shoes, hinge connections between said slices, an inwardly directedVV hollow projectionon each sh'oe,.a U-shaped anchorV link having threaded extremities, openings in said hollow projection for receiving the threaded eXtremitiesof Vsaid anchor link,- nuts orreleasabiwT retaining said anchor links in position on said shoes, additionalopenings in said hollow pro-v jection through which said nuts are-'accessible, and connector links interengaged with and between anchor links of successive shoes to limit the hinge action between'said shoes.

9. truss-type tread belt for crawler mechanisms, the combination of a series of shoes, hinge connections between saidv shoes, an inwardly directedprojection on each shoe f having sockets adjacent the ends-thereof, a

'tl-shaped aiichor'link; the ends ci said anchor link being iiXed in said sockets, and connector links interengaged.with'fand-hy the anchor links of successive shoes to vlimit-the hinge action .between said shoes,.said projection co-l operating with said. anchor link to'v form an uninterrupted guide surface for the ends of said successive connector lin (s.

10. In atruss-typeftread belt for crawler mechanisms, the combination of a plurality or tread shoes, hinge connections'Y therebetween, an anchorlink on' each shoe, and a pair of connector links engaged in the opposite ends of 'each anchor link, eachcf said con- Y V.action between said shoes. `(i5 11. aiguise-.type Ytread belt for crawler tween, a member. centrallyidisposed on each shoe and forming anelongated loop, and single links between successive shoes forming connections between said loops to limit the hinge action between saidshoes, the adjacent ends of successive links beingslidably engagedin an intermediate'loopand movable therein into and out o'engagement witheach other during hinge action between saidshoes.

12. In a truss-typetread belt for crawler mechanisms, the combination .of aplurality of. tread shoes, hingeconnections therebetween, ay member5 projecting from eachgshoe and forming therewithan elongated loop having opposed, guide surfaces extending substantially throughout the length thereof, and single connector links interengaged within the loops of successive shoes and coacting ywith saidloops to limit therhinge action beshoes.

14. In a truss-type tread belt for crawler mechanisms the combination of a plurality of treadslroes, hinge connections betweensaid shoes, a'pair of posts projecting inwardly rfrom each shoe, aV single link embracing the adjacent posts of successive shoes and coacting therewith to limit lthe hinge action Vbetween said shoes, and vmeans for maintaining said links in proper coactiiig'relation withk said posts. 15. In a truss-type treadbeltfor crawler 'Ymechanisms V.the combination of a Vplurality 1 ot tread shoes,xmeans for hingedly connect- 'ing said shoes to form a tread belt,.and a chain within said-belt, said chain .comprising a series ofinterlooped links, .alternate links of said series being fixed to successive shoes, theothers of saidllinks beingmovablelength.- wise of and guided byAv said alternate links, allV of said links beingspaced inwardly from said hinge means andcoacting to limit the hinge action between said shoes.V

In witness whereof, yI hereunto subscribe my name this 7th day .ofDecemben 1927.

- GrEQRGrEA C. JETT.,

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